1. Field of the Invention
The present invention is generally related to a supercharging system for an engine and, more particularly, to a supercharger for a powerhead of an outboard motor in which the air charge is controlled as a function of manifold absolute pressure, barometric pressure, and temperature.
2. Description of the Prior Art
Many different types of supercharger systems are known to those skilled in the art. U.S. Pat. No. 5,937,833, which issued to Kapich on Aug. 17, 1999, describes a control system for a hydraulic supercharger system. The control system is specially adapted to control a supercharger system comprising a hydraulic pump, a supercharger having a hydraulic turbine drive and a compressor driven by the hydraulic turbine drive, a main hydraulic piping means providing a hydraulic circulation loop for hydraulic fluid to flow from the pump to drive the hydraulic turbine drive and back to the pump, and a supercharger bypass system comprising a control bypass valve and a piping means to permit a portion of the hydraulic fluid to bypass the supercharger turbine drive. The control system includes a bypass control valve arranged to close and partially and fully open the controlled bypass valve. The bypass control valve may be a hydraulic valve controlled by the pressure of the compressed air intake to the engine. The bypass control valve may also be a solenoid valve controlled by a pressure switch connected to sense hydraulic pressure and to apply a voltage to the solenoid valve to open or close the valve upon the hydraulic pressure reaching a predetermined value.
U.S. Pat. No. 5,937,832, which issued to Kapich on Aug. 17, 1999, is generally similar to U.S. Pat. No. 5,937,833 which is described above. The control system includes a solenoid arranged to close and partially or fully open the control bypass valve. The solenoid may be controlled by a pressure switch connected to sense hydraulic sense and to apply a voltage to the solenoid to open or close the valve upon the hydraulic pressure reaching a predetermined value. Since the hydraulic pressure increases with engine speed, it is a simple matter to adjust the control system to provide for the hydraulic fluid to drive the supercharger or bypass the supercharger at any predetermined ranges of engine speed. The bypass valve may also be controlled based on engine throttle position. In another preferred embodiment where the turbocharger system comprises an air flow check valve which opens when a turbocharger is providing air to the engine, the bypass valve is also subject to control based on the position on the check valve so that the hydraulic supercharger can be substantially bypassed when the turbocharger is able to provide sufficient air to the engine.
U.S. Pat. No. 5,127,386, which issued to Sowards on Jul. 7, 1992, describes an apparatus for controlling a supercharger. The apparatus includes a compressor having a rotor portion, an inlet, and a discharge. A motor portion of the apparatus has an intake manifold connected to the discharge. A throttle is displaceable between an open and closed position for controlling fluid flow between the discharge and the intake manifold. A bypass return line connects the rotor portion of the compressor to the inlet. A piston valve, moveable between an open location and a closed location, controls flow through the bypass return line. A control line, connecting the intake manifold to the piston rod controls the location of the piston valve. A control valve may be included to control fluid flow through the control line. A computer, which is affected by the operation of the motor, controls the position of the control valve.
U.S. Pat. No. 4,637,210, which issued to Yamamoto on Jan. 20, 1987, describes a supercharge pressure control apparatus of a supercharged engine. A bypass is provided to bypass a supercharger turbine arranged between the intake and exhaust passages. A waste gate valve is attached at one end of the bypass and is coupled to an actuator having a pressure chamber communicated with a connecting passage which is branched at a branch point into the first and second passages. A first port is formed in the intake passage downstream near a suction inlet of a compressor and a second port is formed in the intake passage downstream of the first port. In the stationary operating state, the connecting passage is communicated with the second passage by the charge-over valve, so that a high pressure from the second port acts on the pressure chamber and the supercharged pressure is maintained at a set level. In the acceleration operating state, the connecting passage is communicated with the first passage for a predetermined time, so that a low pressure from the first port acts on the pressure chamber. When the pressure at the first port operates the set level, the pressure at the second port exceeds the set level, so that a supercharged pressure over the set level is supplied into the engine. After a preset time, the connecting passage is communicated with the second passage and the pressure is held at the set level.
U.S. Pat. No. 4,530,339, which issued to Oguma et al on Jul. 23, 1985, describes a supercharger control apparatus for motor vehicles. The apparatus comprises a control device which has as input signals the demand signal for acceleration and an engine rotation speed signal. Based on predetermined ranges of demand signal for acceleration and engine rotational speed and on the input signals, the control device regulates, through an actuator and bypass valve or through an actuator and variable capacity compressor, the amount of supercharging. The supercharge control apparatus allows a non-supercharged state, a maximum supercharged state, or an intermediate supercharged state. In the intermediate supercharged state, the amount of supercharging is in incremental steps to prevent hunting.
U.S. Pat. No. 4,461,149, which issued to Suzuki on Jul. 24, 1984, describes a turbocharger control system for an internal combustion engine. The system comprises a supercharger for applying a supercharge pressure to the engine by driving a compressor with a turbine rotated by the energy of the exhaust gas, and an exhaust gas bypass valve for regulating the amount of the exhaust gas supplied to the turbine. A factor related to the engine combustion state, such as a knocking condition, is detected and a signal representing the condition is generated. At least one output pressure produced from the compressor is modified in accordance with the above-mentioned signal. The pressure thus modified is used for adjusting the opening of the exhaust gas bypass valve thereby to control the supercharge pressure.
U.S. Pat. No. 5,848,582, which issued to Ehlers et al on Dec. 15, 1998, discloses an internal combustion engine with barometric pressure related start of air compensation for a fuel injector. The control system for a fuel injector system for an internal combustion engine is provided with a method by which the magnitude of the start of air point for the injector system is modified according to the barometric pressure measured in a region surrounding the engine. This offset, or modification, of the start of air point adjusts the timing of the fuel injector system to suit different altitudes at which the engine may be operating.
U.S. Pat. No. 6,032,642, which issued to Trumbower et al on Mar. 7, 2000, describes a method for enhanced split injection in internal combustion engines. It describes a method for controlling fuel delivery in a fuel injection system capable of performing a split injection and includes the step of comparing at least one engine operating temperature to a temperature threshold and disabling split injection when the engine operating temperature exceeds the temperature threshold. Disabling split injection in this manner enhances cold temperature engine operating while providing a single injection at higher operating temperatures, as desired. Further, an engine and a computer readable storage medium having information stored thereon representing the instructions executable by an engine controller for comparing at least one engine operating temperature to a temperature threshold are also described. The computer readable storage medium instructions disable split injection when the engine operating temperature exceeds the temperature threshold.
U.S. Pat. No. 5,924,403, which issued to Thomas on Jul. 20, 1999, describes a method for enhanced split injection in internal combustion engines. It describes a method for controlling a compression-ignition internal combustion engine which provides a delivery of multiple fuel injection pulses per cylinder firing with precision of pulse quantities, separation, and timing adequate for transition between split and single injection at any speed and load, without disturbing the primary engine governor. The method compensates for variable operating conditions such as supply voltage, injection pressure, injection pulse separation, and injector actuation latency or rise-time.
U.S. Pat. No. 5,778,858, which issued to Garabedian on Jul. 14, 1998, describes a fuel injection split engine. An automobile includes an engine and an engine controller. The engine includes multiple cylinders. Each cylinder has a fuel injector connected to the engine controller. The engine controller has a first output which activates a first fraction of the fuel injectors. In addition, the engine controller has a second output which activates a second fraction of the fuel injectors. The engine controller also has an input which provides a timing signal synchronous with rotation of the engine and sequencing circuit responsive to the timing signal. The sequencing circuit periodically alternates between the first and second output in synchronization with the rotation of the engine.
U.S. Pat. No. 5,492,098, which issued to Hafner et al on Feb. 20, 1996, describes an apparatus for variably controlling the fuel flow characteristics of a hydraulically actuated injector during an injection cycle. The apparatus includes variable control of actuating fluid pressure and a spill control apparatus associated with the plunger and barrel assembly of the injector. The apparatus can control the initial rate of fuel injection and also provide continuous or split injection throughout the load and speed range of an engine. Performance is controlled by the geometry of the spill control apparatus along with the variably controlled pressure of the actuating fluid supplied to the injector. The apparatus helps reduce engine noise and emissions.
U.S. Pat. No. 5,231,962, which issued to Osuka et al on Aug. 3, 1993, describes a fuel injection control system with split fuel injection for a diesel engine. At startup, a fuel injection control system for the diesel engine injects a pre-jet of fuel into a combustion chamber in synchronism with a signal indicative of an angular position of the crankshaft of the diesel engine. After the pre-jet of fuel has been injected, the fuel injection control system injects a main jet of fuel which is larger in quantity than the injected pre-jet of fuel. Even when the engine rotational speed is low and subjected to variations as at engine startup, the pre-jet of fuel is reliably injected into the combustion chamber at a desired time. The pre-jet of fuel which is injected and ignited prior to the main jet develops an easily ignitable, activated condition in the combustion chamber. The subsequently injected main jet of fuel can thus be easily ignited by the activated condition in the combustion chamber. The diesel engine can be started quickly and smoothly without fail.
U.S. Pat. No. 4,146,006, which issued to Garabedian on Mar. 27, 1979, describes a fuel injection split engine. A circuit is described for a multiple cylinder engine which permits operation of all of the engine cylinders or part thereof in response to engine loads. Different operating modes, incorporating different number of cylinders, are activated in a fuel injection engine in response to varying power demands. Manual switching circuits on the dashboard of the automobile permit the driver to override the automatic system and require that the engine operate in any of its operating modes. When operating in partial modes, a circuit automatically rotates the cylinder banks which are operated to assure uniform engine wear and cooling. Switches are provided on the dashboard to permit the operator to selectively skip certain engine modes in the automatic, load-responsive sequencing of engine operation.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
It would be significantly beneficial, in view of the supercharger systems known to those skilled in the art, to provide a control method for a supercharged engine in which the air charge mass provided to the combustion chambers of the engine is controlled as a function of charge air temperature, charge air pressure, and barometric pressure.
A method for controlling a supercharger, made in accordance with the present invention, comprises the steps of disposing the supercharger in fluid communication within an air stream flowing to a combustion chamber of a cylinder of an engine, selecting a desired magnitude of air per cylinder (APC) to be provided to the combustion chamber of the engine, measuring an actual pressure of charge air provided to the cylinder of the engine, measuring an actual temperature of charge air provided to the cylinder of the engine, providing a throttle valve disposed upstream from the supercharger and the combustion chamber for controlling the amount of air flowing to the inlet of the supercharger, through the supercharger, to the combustion chamber, providing a bypass conduit connecting the outlet of the supercharger to the inlet of the supercharger, and providing a bypass valve within the bypass conduit to control the flow of air from the outlet of the supercharger to the inlet of the supercharger through the bypass conduit.
The method of the present invention further comprises the steps of calculating an actual magnitude of air charge mass provided to the combustion chamber as a function of the actual charge air temperature and the actual charge air pressure, determining a difference between the actual magnitude of charge air and the desired magnitude of charge air, and controlling the position of the bypass valve as a function of the difference between the actual magnitude of charge air and the desired magnitude of charge air.
The method of the present invention can further comprise the steps of measuring an actual barometric pressure of the air surrounding the engine and calculating a ratio of the actual charge air pressure to the actual barometric pressure (i.e. xe2x80x9cMAP/BAROxe2x80x9d). It further comprises the steps of calculating an actual magnitude of air charge mass provided to the combustion chamber as a function of the actual charge air pressure, the ratio (i.e. xe2x80x9cMAP/BAROxe2x80x9d), and the actual charge air temperature.
Certain embodiments of the present invention measure the actual pressure at a location in fluid communication with the charge air between the outlet of the supercharger and the combustion chamber. The actual charge air temperature can be measured at a location in fluid communication with the charge air between the outlet of the supercharger and the combustion chamber. A preferred embodiment of the present invention further comprises the step of providing a microprocessor connected in signal communication with the temperature sensor for measuring the actual charge air temperature of air provided to the cylinder and a pressure sensor for measuring an actual charge air pressure (i.e. xe2x80x9cMAPxe2x80x9d) provided to the cylinder, wherein the microprocessor performs the calculating and determining steps. The calculating step can calculate the air per cylinder (APC) for the one or more cylinders according to a relationship which defines the air per cylinder as being equal to the manifold absolute pressure (MAP) multiplied by the swept volume of the cylinder and also multiplied by the volumetric efficiency (i.e.{acute over (xcex7)}) with that product being divided by the product of the ideal gas constant R multiplied by the charge air temperature measured within the air intake manifold. The engine can be a powerhead of a marine propulsion system, such as an outboard motor.